Simple Coal Workers Research Articles

Black Lung: Old Disease, New Lessons

Previous to 2016, cases of progressive massive fibrosis secondary to mining exposure had dwindled and were considered nearly eradicated. However, over 40 new cases were recently discovered in Kentucky, indicating a resurgence of a previously rare disease. We herein report a case of a 44-year-old male underground coal miner from Appalachia with fifteen years coal mining dust exposure who presented with four years of productive cough, dyspnea upon exertion and wheezing for an occupational pneumoconiosis evaluation. Since 2016, he suffered a precipitous decline in lung function consistent with restrictive lung disease and concomitant progression from simple coal workers’ pneumoconiosis to progressive massive fibrosis. In particular, his chest x-ray shows classic findings of “angel wings” caused by large fibrotic masses in both lungs. This case, as well as the several other new cases, call attention to the resurgence of PMF and requires examination of the factors contributing to its recent rebound.

Lung Pathology in U.S. Coal Workers with Rapidly Progressive Pneumoconiosis Implicates Silica and Silicates.

Recent reports of progressive massive fibrosis and rapidly progressive pneumoconiosis in U.S. coal miners have raised concerns about excessive exposures to coal mine dust, despite reports of declining dust levels. To evaluate the histologic abnormalities and retained dust particles in available coal miner lung pathology specimens, and to compare these findings with those derived from corresponding chest radiographs. Miners with severe disease and available lung tissue were identified through investigator outreach. Demographic as well as smoking and work history information was obtained. Chest radiographs were interpreted according to the International Labor Organization classification scheme to determine if criteria for rapidly progressive pneumoconiosis were confirmed. Pathology slides were scored by three expert pulmonary pathologists using a standardized nomenclature and scoring system. Thirteen cases were reviewed, many of which had features of accelerated silicosis and mixed dust lesions. Twelve had progressive massive fibrosis, and 11 had silicosis. Only four had classic lesions of simple coal workers' pneumoconiosis. Four had diffuse interstitial fibrosis with chronic inflammation, and two had focal alveolar proteinosis. Polarized light microscopy revealed large amounts of birefringent mineral dust particles consistent with silica and silicates; carbonaceous coal dust was less prominent. On the basis of chest imaging studies, specimens with features of silicosis were significantly associated (P = 0.047) with rounded (type p, q, or r) opacities, whereas grade 3 interstitial fibrosis was associated (P = 0.02) with the presence of irregular (type s, t, or u) opacities. Our findings suggest that rapidly progressive pneumoconiosis in these miners was associated with exposure to coal mine dust containing high concentrations of respirable silica and silicates.

Emphysema and chronic obstructive pulmonary disease in coal miners

Coal mining remains a major industry that has workers at risk for developing chronic lung disease. Aside from simple coal workers' pneumoconiosis and progressive massive fibrosis, the development of emphysema and obstructive lung disease independent of smoking may be underappreciated. This article reviews more recent studies that may help rectify this faulty view. Cumulative exposure to coal dust is a significant risk factor for the development of emphysema and has an additive effect to smoking. Increased coal dust exposure is associated with increased risk of death from chronic obstructive pulmonary disease (COPD). In newly employed coal miners, bronchitic symptoms are associated with a rapid decline in lung function within 2 years after starting work. In evaluating impairment, the chest radiograph may be helpful as a marker of exposure but the diffusing capacity is most correlated with dyspnea, whereas the emphysema computed tomography score has good association with expiratory flow limitation. Latest studies further support the association of emphysema and COPD with coal dust exposure. Increased cumulative exposure may also increase risk of death from these diseases.

Wood charcoal and activated carbon dust pneumoconiosis in three workers

Data on prevalence of lung diseases due to inhalation of carbonaceous materials other than mineral coal is very limited. We present three cases of wood charcoal pneumoconiosis, two due to activated carbon, and one from wood charcoal artisan handling. To our knowledge, no clinical cases of wood charcoal pneumoconiosis, from artisan handling has been published so far. The three cases had their X rays classified by two B-readers as p/q round opacities with profusion ranging from 2/2 to 3/3. HRCT of two of them showed a diffuse centrilobular ground glass nodular pattern with subpleural small areas of consolidations. Transbronchial biopsies showed deposition of black pigment in the bronchiolar interstice similar to the histological appearance of simple coal workers pneumoconiosis, with no signs of fibrosis. Spirometry showed no abnormalities in the three cases. The authors point out to a probably underestimated respiratory occupational risk related to wood charcoal manipulation, which must be addressed mostly in developing countries, where deficient workplace conditions can lead to exposure above limit levels.

From Quartz Hazard to Quartz Risk: the Coal Mines Revisited

Following the classification of quartz as a human carcinogen by the IARC, many standard-setting committees are currently trying to convert this hazard into their national or EU standards. Since human data to set a safe exposure limit for quartz are limited, we hypothesized that lung burden data on quartz in coal miners' lungs after lifetime exposure could be used to set a non-carcinogenic lung burden of quartz, and that this might be valid for other groups occupationally exposed to quartz. A review of data shows that lungs of coal miners with simple coal workers' pneumoconiosis (sCWP) typically contain up to 30 g of dust, and in one specific study lung burdens between 0.7 and 1.7 g of quartz were associated with macules only, and no sCWP. Assuming independent actions of coal and quartz and no clearance of quartz, and sCWP as a prerequisite for lung cancer due to quartz exposure in coal mine dust, a simple kinetic approach was applied. A no observed adverse effect level (NOAEL) for quartz of between 0.03 and 0.13 mg/m3 (40 yr exposure) is derived, but it is concluded that more refined physiologically based pharmacokinetic modelling is needed for a better estimate, also including interindividual differences in lung clearance. Considering the independent effects of, and the well-known interaction between coal and quartz, these data could be important to other workplaces with usual mixed-dust exposure.

Clinical Significance of Plasma TGF-beta1 in Coal Workers' Pneumoconiosis

Background Coal workers' pneumoconiosis is a fibrotic lung disease resulting from chronic inhalation of coal dust. The precise mechanism of lung fibrosis in coal workers' pneumoconiosis is uncertain. However, a relationship between the stimulation of fibroblast proliferation and collagen production by mediators released from inflammatory and resident lung cells is thought to be a major factor. The transforming growth factor-β(TGF-β), a multifunctional cytokine and growth factor, plays a key role in the scarring and fibrotic processes due to its ability to induce extracellular matrix proteins and modulate the growth and immune function of many cell types. To determine the involvement of TGF-βin the development of lung fibrosis in coal workers' pneumoconiosis, the TGF-β1 level in plasma was measured in patients with coal workers' pneumoconiosis. Methods Plasma was collected from 40 patients with coal workers' pneumoconiosis (20 with simple coal workers' pneumoconiosis and 20 with complicated coal workers' pneumoconiosis) and from 10 normal controls. The ELISA method was used to measure the plasma TGF-β1 concentration. Results Compared to the control group (0.63±0.18 ng/mL), there was no significant difference in the plasma TGF-β1 level in patients with simple coal workers' pneumoconiosis (0.64±0.17 ng/mL) (p>.05). However, in patients with complicated coal workers' pneumoconiosis the plasma TGF-β1 level (0.79±0.18 ng/mL) was significantly higher than in patients with simple coal workers' pneumoconiosis and control group (p<0.05). Conclusion The data suggests that TGF-β1 has some influence in the development of lung fibrosis in coal workers' pneumoconiosis.

Respiratory symptoms and pulmonary function in coal miners: Looking into the effects of simple pneumoconiosis

Background Although severe impairment of pulmonary function is believed to occur commonly in complicated pneumoconiosis, the relationships of simple coal workers' pneumoconiosis (CWP) to pulmonary function and respiratory symptoms have remained under debate. The study aims to investigate if simple pneumoconiosis is associated with significant impairment of pulmonary function and increased risk of respiratory symptoms. Methods Spirometry and diffusing capacity were performed in 205 miners with simple CWP and 289 without X ray evidence of pneumoconiosis, who were selected from a large underground coal mine in China. A questionnaire on occupational history and respiratory symptoms including breathlessness, chronic cough, and phlegm was administered. The presence or absence of emphysema on their X-ray films was also evaluated. Logistic regression and multiple linear regression analysis were applied to estimate the independent effect of CWP on respiratory symptoms and parameters of pulmonary function. Results On the average, the miners with CWP had lower values of pulmonary function and higher prevalences of respiratory symptoms, and emphysema than did those without. The simple CWP was associated with increased risk of the respiratory symptoms after adjusting for age, smoking, and years underground. Regression analysis showed that the CWP had significantly independent effects on parameters of pulmonary function. Even when the effects of emphysema, respiratory symptoms indicating chronic bronchitis were taken into consideration, the significant relationship between CWP and decrements in FVC and diffusing capacity remained. Conclusion The findings of this study are consistent with simple CWP being a contributor to significant decrements in pulmonary function, and to increased risk of respiratory symptoms. Am. J. Ind. Med. 35:124–131, 1999. © 1999 Wiley-Liss, Inc.

Respiratory symptoms and pulmonary function in coal miners: looking into the effects of simple pneumoconiosis.

Although severe impairment of pulmonary function is believed to occur commonly in complicated pneumoconiosis, the relationships of simple coal workers' pneumoconiosis (CWP) to pulmonary function and respiratory symptoms have remained under debate. The study aims to investigate if simple pneumoconiosis is associated with significant impairment of pulmonary function and increased risk of respiratory symptoms. Spirometry and diffusing capacity were performed in 205 miners with simple CWP and 289 without X ray evidence of pneumoconiosis, who were selected from a large underground coal mine in China. A questionnaire on occupational history and respiratory symptoms including breathlessness, chronic cough, and phlegm was administered. The presence or absence of emphysema on their X-ray films was also evaluated. Logistic regression and multiple linear regression analysis were applied to estimate the independent effect of CWP on respiratory symptoms and parameters of pulmonary function. On the average, the miners with CWP had lower values of pulmonary function and higher prevalences of respiratory symptoms, and emphysema than did those without. The simple CWP was associated with increased risk of the respiratory symptoms after adjusting for age, smoking, and years underground. Regression analysis showed that the CWP had significantly independent effects on parameters of pulmonary function. Even when the effects of emphysema, respiratory symptoms indicating chronic bronchitis were taken into consideration, the significant relationship between CWP and decrements in FVC and diffusing capacity remained. The findings of this study are consistent with simple CWP being a contributor to significant decrements in pulmonary function, and to increased risk of respiratory symptoms.

Mechanisms and Mediators in Coal Dust InducedToxicity: a Review

Chronic inhalation of coal dust can cause several lung disorders, including simple coalworkers pneumoconiosis (CWP), progressive massive fibrosis (PMF), chronic bronchitis, lungfunction loss, and emphysema. This review focuses on the cellular actions and interactions ofkey inflammatory cells and target cells in coal dust toxicity and related lung disorders, i.e.macrophages and neutrophils, epithelial cells, and fibroblasts. Factors released from or affectingthese cells are outlined in separate sections, i.e. (1) reactive oxygen species (ROS) and relatedantioxidant protection mechanisms, and (2) cytokines, growth factors and related proteins.Furthermore, (3) components of the extracellular matrix (ECM), including the modifying role ofROS, cytokines, proteases and antiproteases are discussed in relation to tissue damage andremodelling in the respiratory tract.It is recognised that inhaled coal dust particles are important non-cellular and cellularsources of ROS in the lung, and may be significantly involved in the damage of lung target cellsas well as important macromolecules including α-1-antitrypsin and DNA. In vitro and in vivo studies with coal dusts showed the up-regulation of importantleukocyte recruiting factors, e.g. Leukotriene-B4 (LTB4), Platelet Derived Growth Factor(PDGF), Monocyte Chemotactic Protein-1 (MCP-1), and Tumor Necrosis Factor-α(TNFα), as well as the neutrophil adhesion factor Intercellular Adhesion Molecule-1(ICAM-1). Coal dust particles are also known to stimulate the (macrophage) production ofvarious factors with potential capacity to modulate lung cells and/or extracellular matrix,including O2 · −, Hfn2fn2Nitric oxide is strictly not to beconsidered as ROS (i.e. oxygen-centered radical), but comprises a major source of reactive(oxygen) species, including ONOO−, OH·, and singlet oxygen.O2, and NO·, fibroblast chemoattractants (e.g. TransformingGrowth Factor-β (TGFβ), PDGF, and fibronectin) and a number of factors thathave been shown to stimulate and/or inhibit fibroblast growth or collagen production such as(TNFα, TGFβ, PDGF, Insulin Like Growth Factor, and Prostaglandin-E2). Further studies are needed to clarify the in vivo kinetics and relative impact ofthese factors.

Risks of Occupational Respiratory Diseases among U.S. Coal Miners

Abstract The excess (exposure-attributable) risks of certain respiratory diseases and outcomes were estimated for U.S. coal miners exposed to respirable coal mine dust for various durations and concentrations, including a 45-year working lifetime at the current 2-mg/m3 standard. Multiple linear and logistic regression models were used to compute predicted prevalence and excess risk of disease, using data and regression results from published epidemiological studies of U.S. coal miners. Disease outcomes evaluated include simple coal workers' pneumoconiosis, progressive massive fibrosis, and clinically significant deficits in lung function, measured as forced expiratory volume in 1 second of < 80% or < 65% of predicted normal values. Point estimates of excess risk of progressive massive fibrosis ranged from 1/1000 to 167/1000 among coal miners exposed to respirable coal mine dust at a mean concentration of 2 mg/m3 for 45 years. This range reflects coal rank and study differences. Point estimates for an exce...

High-Resolution CT in Simple Coal Workers' Pneumoconiosis: Lack of Correlation With Pulmonary Function Tests and Arterial Blood Gas Values

We examined 21 miners by means of standard chest radiography, high-resolution computerized tomography (HRCT), pulmonary function tests, and resting arterial blood gas levels. Using the ILO/UC classification of pneumoconiosis, 7 miners had category 1/0 or 2/1 simple coal workers' pneumoconiosis (CWP). By HRCT, nodules were identified in 12 miners; 4 of 9 were classified as category 0/0 CWP; 2 of 5, 0/1 CWP; 5 of 6, 1/0 CWP; and 1 of 1, 2/1 CWP by chest radiograph. Focal emphysema was identified by HRCT in 7 miners; 4 of 9 were classified as 0/0 CWP; 2 of 5, 0/1 CWP; and 1 of 6, 1/0 CWP by standard chest radiography. Four miners with definite nodules confirmed by HRCT had focal emphysema, while three without nodules had focal emphysema. Pulmonary function testing was not different between miners with or without CWP by standard chest radiography, nor was it different between miners with or without definite nodules evidenced by HRCT. No difference in resting oxygenation was found between any group of miners. The presence of focal emphysema confirmed by HRCT did not significantly affect pulmonary function tests on resting arterial blood gas values. There was, however, a significantly lower FEV1 and mean forced expiratory flow during the middle half of forced vital capacity with lifetime nonsmoking miners. The presence of CWP on chest radiography was significantly correlated with smoking cigarettes but not the years of mining. The presence of nodules on HRCT approached a significant correlation with cigarette smoking, but focal emphysema did not. For detecting evidence of coal dust accumulation in lung parenchyma and identifying focal emphysema, HRCT was more sensitive than standard chest radiography. However, despite earlier detection of parenchymal abnormalities, abnormal pulmonary function attributable to coal dust could not be identified.

Resting Gas Exchange in Nonsmoking Bituminous-Coal Miners with Simple Pneumoconiosis

Gas exchange at rest under normoxic conditions was studied in 2,297 nonsmoking bituminous-coal miners with and without simple coal workers' pneumoconiosis (CWP). Measurements of arterial oxygen tension (Pao2) and arterial carbon dioxide tension (Paco2) from blood gas samples obtained at rest in the seated position were used to calculate the alveolar-arterial oxygen tension difference, (A-a)Do2, using the classic alveolar-air equation. We then recalculated the (A-a)Do2 using the age-predicted Pao2 for each miner. The difference between the actual and the predicted (A-a)Do2 was measured and the mean difference for each category of simple CWP was analyzed. We found no evidence that the resting gas exchange differs significantly from the age-predicted (A-a)Do2 in the nonsmoking bituminous-coal minor with simple CWP. Likewise, there is no significant change in (A-a)Do2 with change in the category of simple CWP.

Spontaneous and stimulated release of tumor necrosis factor-alpha (TNF) from blood monocytes of miners with coal workers' pneumoconiosis.

It is generally accepted that fibrotic lung diseases are mediated by macrophage-derived cytokines. We investigated the release of the monokine tumor necrosis factor-alpha (TNF) from blood monocytes in a group of 66 coal miners and 12 non-dust-exposed individuals. Twenty-seven miners had simple Coal Workers' Pneumoconiosis (CWP). Control miners (n = 39) were matched with respect to age, years underground, and smoking. Monocytes were assayed for TNF release, spontaneously or in response to soluble (endotoxin) or particulate (coal mine dust, silica) stimulation. TNF was measured with a TNF-specific ELISA. Monocytes of all subjects responded to stimulants by the release of TNF. Dust-exposed controls' monocytes revealed higher TNF release as compared to normal controls. The greatest discriminator between control miners and cases (CWP) was coal mine dust-induced TNF release. Interestingly, the largest difference was observed between controls and those cases with a small number of opacities (0/1, 1/0, 1/1, and 1/2), giving an odds ratio of 6.3 to find an individual with a "high" dust-induced TNF release in the patient group.

Relationship between type of simple coalworkers' pneumoconiosis and lung function. A nine-year followup study of subjects with small rounded opacities (November 1981)

Relationship between type of simple coalworkers' pneumoconiosis and lung function. A nine-year followup study of subjects with small rounded opacities (November 1981)

Relationship between type of simple coalworkers' pneumoconiosis and lung function. A nine-year follow-up study of subjects with small rounded opacities.

One hundred and twenty-five men who were identified in 1968 as having the simple pneumoconiosis of coalworkers were re-examined nine years later when their mean age was 59.6 years. On both occasions the lung function and response to exercise were assessed. There was no evidence for progression of simple pneumoconiosis between the surveys, but 14 had developed small irregular opacities on their chest radiographs and 28 showed early changes of progressive massive fibrosis (PMF). After allowing for the effects of smoking and of exposure to coal dust, subjects with both p and r types of simple pneumoconiosis exhibited a reduced transfer factor compared with subjects having q-type opacities; subjects with r-type opacities also showed an increased pulmonary elastic recoil pressure. The presence of irregular opacities, independent of rounded opacities, was associated with a low transfer factor and decreased slope of phase III of the single breath oxygen test. Subjects who developed PMF between 1968 and 1978 had p or r opacities more often than q opacities: these subjects had an increase pulmonary elastic recoil pressure. The development of PMF was also associated with physiological evidence of airways obstruction. The changes in subjects with r opacities are consistent with the presence of space occupying lesions that may progress to PMF. Subjects with p opacities have physiological evidence of emphysema as do some subjects with established PMF. Irregular opacities may reflect the presence of both emphysema and diffuse fibrosis. There is need for more morbid anatomical evidence on the underlying pathology.

Effects of inhaled diesel emissions and coal dust in rats.

Rats were exposed to coal dust and diesel exhaust emissions, separately and in combination, for 20 months to evaluate the potential health effects of these specific mine air materials. The diesel exhaust was produced by an engine operated in a load, no-load mode and acceleration, deceleration cycle. It was also modified to simulate an inefficiently tuned engine. Exposure to coal dust was performed in a whole-body rodent inhalation system. Mortality, body weight and hematologic parameters examined were normal compared with those of control rats. Lesions observed were primarily restricted to the lungs and were similar to those described for simple coal workers' pneumoconiosis (CWP). Lesion progression and severity was related to exposure duration and exposure material. Alveolar bronchiolization, though not reported in human CWP, was present in the lungs of some rats in all exposure groups except the control animals.

Pulmonary conductance and elastic recoil relationships in asthma and emphysema.

Pulmonary conductance and elastic recoil relationships in asthma and emphysema.

Relationship of pulmonary impairment in simple coal workers' pneumoconiosis to type of radiographic opacity.

<b>Seaton, A., Lapp, N. L., and Morgan, W. K. C. (1972).</b><i>Brit. J. industr. Med.,</i><b>29,</b> 50-55. <b>Relationship of pulmonary impairment in simple coal workers9 pneumoconiosis to type of radiographic opacity.</b> From a group of 1 461 working coal miners who participated in an epidemiological study, 223 men with simple pneumoconiosis were selected on the basis of the type of small rounded opacity noted to be present in their chest films. No differences in spirometry or lung volumes were found between those with the micronodular (q) and those with pinhead (p) opacities. Twenty-five non-smoking miners with category 2 or 3 simple coal workers9 pneumoconiosis were subsequently selected for further pulmonary function testing. Studies of lung volumes and pulmonary mechanics showed no difference between those with the pinhead and micronodular types of opacity; however, transfer factor was somewhat lower in those with the former.

Pulmonary hemodynamics in symptomatic coal miners.

Forty-seven coal miners, selected because they were symptomatic, underwent studies of pulmonary hemodynamics at rest and during exercise. They were divided into two groups depending on the absence or presence of airway obstruction. Of the 23 in the group without airway obstruction, one had a high mean pulmonary artery pressure at rest and another 3 showed increase of this pressure during exercise. All 4 had the pinpoint type of simple pneumoconiosis. Of the subjects with obstruction, 7 of 24 had pulmonary arterial hypertension that could be accounted for by airway obstruction or complicated pneumoconiosis, whereas one with less severe obstruction had pinpoint opacities on his chest radiograph. Abnormalities of alveolar-arterial oxygen gradient, arterial oxygen tension, and dead space ventilation were common in both groups, but were only significantly related to pulmonary artery pressure in the group with obstruction. These results indicate that pulmonary arterial hypertension can occur in the pinpoint type of simple coal workers pneumoconiosis in the absence of obstructive airway disease, although its infrequency in this selected group of symptomatic miners suggests that it is very uncommon.